The Colombian forward, whose performances since signing a three-year deal in the summer of 2017 have caught the eye of a string of top clubs, made his international debut in September last year.
He has scored 28 goals from 41 appearances this season under Steven Gerrard.
Speaking to the Light Blues website, the 22-year-old said: “It did not take me long to agree this extension because my career has progressed quicker and better than I could have expected when I joined this great club.
“I have come to realise just how special Rangers is and what it means to so many people around the world. Also, I feel a strong connection with the fans and they have made me feel special.
“They have been terrific for me and always back me which makes me want to score for them and then celebrate with them. “I want to score many more goals for them, Rangers, and the manager, who has helped me so much, before this season ends.”
Highlighting Morelos’ scoring record as he welcomed the contract extension, Gerrard added: “It’s always important at big clubs like this one to make sure your top players are secured long term. Alfredo has been excellent for Rangers.
“He is a competitive individual and he is a winner. He is what Rangers needs and it is pleasing that Alfredo feels so much at home with us that he is willing to commit.”
Morelos scored 18 goals last season and was voted Young Player of the Year by Rangers fans.
He has twice renewed his contract with the Ibrox club in the last 12 months alone, extending his stay by 12 months in March 2018, tying him to Rangers until 2021, before penning another extension on the eve of an Old Firm clash in September 2018, keeping him at the club until 2022.